H8SSLASH2224 datasheet(574/1071 Pages) RENESAS

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Section 14 IEBus™ Controller (IEB) [H8S/2258 Group]

Rev. 5.00 Aug 08, 2006 page 488 of 982

REJ09B0054-0500

The slave unit returns the acknowledgement when the slave addresses match and the parities of the

master and slave addresses are correct. When either of the parities of the master and slave

addresses is wrong, the slave unit decides that the master or slave address is not correctly received

and does not return the acknowledgement. In this case, the master unit enters the waiting (monitor)

state, and communications end.

In the case of broadcast communications, the slave address is used to identify the type of broadcast

communications (group or general) as follows:

• When the slave address is H'FFF: General broadcast communications

• When the slave address is other than H'FFF: Group broadcast communications

Note: The group number is the upper 4-bit value of the slave address in group broadcast

communications.

(4) Control Field

The control field is a field for transmitting the type and direction of the following data field. The

control field is comprised of control bits, a parity bit, and an acknowledge bit.

The control bits include four bits and are output MSB first.

The parity bit is output following the control bits. When the parity is correct, and the slave unit can

implement the function required from the master unit, the slave unit returns the acknowledgement

and enters the message length field output state. However, if the slave unit cannot implement the

requirements from the master unit even though the parity is correct, or if the parity is not correct,

the slave unit does not return the acknowledgement, and returns to the waiting (monitor) state.

The master unit enters the subsequent message length field output state after confirming the

acknowledgement.

When the acknowledgement is not confirmed, the master unit enters the waiting (monitor) state,

and communications end. However, in the case of broadcast communications, the master unit

enters the following message length field output state without confirming the acknowledgement.

For details of the contents of the control bit, see table 14.4.

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